Underwater Camera Housing Fact-File

An Underwater Camera Housing is quite simply an external hard casing that fits around a non-waterproof camera allowing underwater photography without the expense of a fully waterproof digital camera. Underwater camera housings are made waterproof through a system of silicone o-rings at all the crucial joints.

An underwater camera housing is specific to the camera and so may not be available for all makes and models. They can be made from several different materials ranging from inexpensive plastic to high-priced aluminium cases. Canon WP-DC600 for IXUS v2All underwater camera housings for example, are outfitted with controls knobs that access the camera inside. This allows the photographer to use of most of the camera's normal functions.

Some underwater camera housings may also have connectors to attach external flash units. While basic housings allow the use of the flash on the camera, which may not be sufficiently powerful or may be improperly placed for underwater applications, more advanced underwater camera housings redirect the signal to fire a slave strobe via a fibre optic cable.

Underwater photographers generally use either wide-angle lenses or macro lenses, both of which allow close focus, thereby eliminating the need to have excessive water between the camera and subject. There are, however, still some optical issues with using cameras inside a watertight housing. Because of refraction, the image coming through the glass port will be distorted, and in particular when using wide-angle lenses. The solution is to use a dome-shaped or fish-eye port, which corrects this distortion.

Most manufacturers make these dome ports for their underwater camera housing, often designing them to be used with specific lenses to 'maximize their effectiveness' and make sure you buy from them!

The Nikonos series allows the use of water contact optics. Which are lenses designed to be used ONLY whilst submerged, without the ability to focus correctly when used in air!

There is also a problem with some digital cameras which do not have sufficiently wide lenses built into the camera. To solve this, there are camera housings made with supplementary optics in addition to the dome port, making the apparent angle of view wider.

Some housings also allow for the use of wet-coupled lenses, which thread on to the exterior of the lens port and increase the field of view. These wet-coupled lenses may be added or removed underwater allowing for both macro and wide angle photography on the same dive.

With macro lenses, the distortion caused by refraction is not an issue, so normally a simple flat glass port is used. In fact, refraction actually increases the magnification of a macro lens, so may be considered a benefit to the photographer who may be trying to capture very small subjects.

Digital cameras hold many more shots than standard cameras with photographic film (which rarely holds more than 36 frames). This is perhaps the primary advantage of using a digital camera underwater, since it is impossible to change photographic film underwater. The second reason being instant approval, ie, you can see the image immediately on the view screen, which is why virtually all underwater photographers now use digital cameras.

So if your current digital camera has an underwater housing available, you may consider buying one rather than going to the expense of a new, fully waterproof camera.